Electrical translating device



May 24, 1927..

v M. c. HOPKINS ELECTRICAL TRA'NSLATING DEVICE Filed June 11. 1925 3 Sheets-Sheet 1 INVENTOR M07005 6. b ah/75 BY 'ATTORNEY May 24 1927} 5 1,630,010 M. c. HOPKINS V ELECTRICAL TRANSLATING DEVICE Filed June 11. 1925 3 Sheets-Sheet 2 mvzmog Marcus Z. fi op%ma ATTORNEY5 .May 24,1927.

H 1,630,010 M. c. HOPKINS ELECTRICAL TRANSLATING DEVICE Filed June 11. 1925 3 Sheets-Sheet 3 a fir w la 7 lNVENTO R 6 Mara/J [/7 0/7%l fi.5

BY fa '{pm f M ATTORNEYS Patented May 24, 1927.

UNITED STATES PATENT-former...

MABC US C. HOPKINS; 0F BROOKLYN, NEW YORK, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO HOPKINS CORPORATION, A CORPORATION OF DELAWABEJ ELEGIRICAL TBANSLATING DEVICE.

Appication filed June 11, 1925. Serial No. 36,562.

The present invention relates to loud speakers for use with radio receiving sets andlme wiretranslation into sound.

'Itis an object of the present invention to 5 provide an improved and simplified. electrical movement or electromagnetic actuating mechanism which may be manufactured at low cost without detracting in any degree from the quality of results obtainable in op-- i nected to sound producing means, such as a conical diaphragm. The diaphragm here illustrated is particularly suited for mounting within a cabinet but diaphragms of other construction may also be used with this electrical movement with good results.

Other objects and advantages of themes ent invention will become clear from the following detailed description which is to be taken in conjunction with the accompanying drawings wherein Fig. 1 is a rear elevational view of a loud speaking instrument in accordance with this invention;

Fig.2 is a cross-sectional view taken approximately along the vertical center line of Fig. '1.

Fig. 3 is a fragmentary elevational view.- 'partly. in cross-section, showing details of construction of the electro-magnetic actuating mechanism;

Fig. 4 is a cross sectienal'view taken along the line H of Fig. '3;

Fig. 5 is a fragmentary elevational view:

- of the peripheral portion of a conical diaphragm,

periphery of the diaphragm is slitted and partly cut away so as to form a considerable number of relatively may be easily bent into the desiredplane;

Fig. (Sis a cross-sectional view of the peripheral portion of the diaphragm shown in Fig. 5,

Figs. 7 and 8 are elevational-and crosssectional views respectively showing the peripheral portion of the diaphragm illustrated in Figs. 5 and 6, but bentinto a plane which is normal to the axis of the diaphrag l, a

Figs. 9 and 10 are elevational and cross- 96 sectional views of the peripheral portion 01$ illustrating one way in which the small sectors which the diaphragm slitted radially but in which the sectors thereby formed have not been cut away as in the case of the diaphragms of Figs. 5 to 8, inclusive,

Figs. -11 and 12 are elevational and crosssectional views similar to Figs. 9 and 10, but showing the sectors bent into, a plane normal to the axis of the diaphragm, and

Figs. 13 and 14 are elevational and crosssectional views of a modified form of movement wherein the armature or reed is yieldingly supported at one end.

In Figs." land 2, the rectangular wooden framework 1, together with the cove s-2 and 3 form a casing structure for the loud speaking instrument which comprises a conical diaphragm 4, an electromagnetic actuating'inechanism 5, andv a cast metal spider '6 to which the diaphragm 4 is attached and on which the electromagnetic actuating mech anism 5 is, mounted. The conical diaphragm 4 is preferably of large diameterperipheral portion id slitted radially as illustrated in Figs. 9, 10, 11 and 12 wherein the radial slits are represented by reference numeral 4. In Fig. 9 the slits 4 are shown closed as a result of the fact that the sectors formed by these slits are lying ,in the'plane of the cone as indicated by Fig. 10/

' In Fig. 11 the slits P are shown open the openings being the result of the sectors being bent intoa plane normal to the axis of the coneas indicated by Fig. 12.- The edges of the peripheral sectorsare secured to the peripheral rim of spider 6. .This may be accomplished by cementing. As indicated at 4 inFigs. 1 and 2 there is a considerable margin between the inner edge oi the spider rim to which the cone is attached and the inner radius of the peripheral sectors. The marginal portion 4 bends quite readily thereby permitting free bodily vibratory movement of the cone. In order to further weaken the resistance to vibration, the peripheral sectors of the diaphragm may be cut away as indicated at 4 in Figs. 5. and 7. The triangular openings formed by cutting away the sectors may be as large as anism is readily accessible.

Claims on a diaphragm so constructed and so mounted are made in my copending application, Serial No. 36,563 filed June The electrical movement or electromag netic actuating mechanism comprises a U-shaped permanent magnet 9, to each extremity of which is secured an angle iron- 10, 11, To the angle iron 10 is .attached a bifurcated soft iron pole shoe 12, betweenthe arms of which is inserted a specially formed member 13 of molded insulating material such as hard rubber or bakelite. The member 13 is provided with openings into each of which is inserted an electromagnet.coil 14, 15. In the arms of the soft iron shoe 12 there are secured threaded studs 16, 17 which. function as adjustable pole pieces. The unthr'eaded portions of these studs extend through the centers of the coils 14, 15, respectively, and are slotted to reduce eddy currents. A. rigid soft iron or steel armature 18 is rigidly attached at one end to the angle iron 11-being preferably riveted thereto as shownand its free end portion is disposed substantially mid-way between the opposing ends of the pole pieces 16, 17. At a point along the mid portion of armature 18 thereis secured a rod or connecting link 19, one end of which. is attached to the cone 4. The connection between the link 19 and cone 4 is made through the medium of a hollow bolt 20, through which the link 19 passes and in which the link may be secured by a transverse set screw. In order to prevent damage to the paper cone, its central portion is secured between two metal conical washers 21, 22 which are clamped togetherv by means of the bolt 20 and nut 23-.

The actuating mechanism forms a self contained unit and is attached to the spider The spider 6 is formed with an .ing is helpful, and important.

should be obtained when the normal magnetic' attraction between one pole piece and the armature is equal and opposite to the magnetic attraction between the other pole piece and the armature.

If the instrument is operated through a transformer and has no normal direct current flowing through its coils'it will general ly be found that the-two air gaps may be equal or substantially so. But if there is a normal direct/current flowing, through its coils, as is the case when it is connected directly in the output circuit of a vacuum tube amplifier, it may be found necessary to adjust one or both of the air gaps so that they are not equal when no current flows.

When the current flowing through coils 14,15 fluctuates, the equilibrium of magnetic forces acting on the armature becomes upset and the" armature is accordingly attracted toward one or the other .pole pieces, depending upon the character of the current-fluctuation. The amplitude of movement of the armature is proportional to the amplitude of the current fluctuation. Accordingly, if the current fluctuations corre spond with sound waves, the armature will vibrate with the same frequency and with an amplitude proportionate to the amplitude of the sound waves which caused the current fluctuations. The vibrations of the armature are short and powerful. The armature being of iron or steel and relatively thick and stiff has a natural period above audibility. The natural elasticity of armature 18 is suflicient to permit the flexing of it, but the armature is so stiff and s0 SUP ported at one end that it cannot strike the adjustable pole toward which it moves. The exact point at which rod 19 can best be attached to armature 18 lies about midway of the length of the armature and depends somewhat on the thickness and stiffness of the armature, and on the weight and other characteristics of the diaphragm to which rod 19 is rigidly attached. The exact point can. best be found by trial.

The diaphragm which can best be used with this electrical movement is of the conical type and preferably not'lessthan nine inches in diameter. The fibrous material of which the cone is made should be light in weight and relatively stiff. A porous paper, the individual fibers of which are tightly interlocked with one another and have been rendered stiff by sizing and aging will'serve well. Stiffness or brittleness made by filling the interstices between the fibers of the paper, as with varnish, does not help. Free suspension of the cone so that it may move as a whole without local warping or bend- In my copending application above referred to I have explained more in detail the advantages of the freely suspended cone as disclosed and everkind ofcone is used with the electrical .,movcme-nt here disclosed, best results, ac-

cording to my experience, can be had by giving to the cone, as a whole, a freedom of bodily movement and a freedom from local bending and distortion. By thus coordinating the diaphragm to the electrical movement a highly satisfactory loud speaker can be obtained. Its tonal characteristics can be varied somewhat by changing the weight or stiffness of the vibratory armature or reed, or by changing the weight, size or thickness of the fibrous cone.

The modification illustrated in Figs. 13 and 14 differs in some respects .from the to the middle .of which is riveted or otherwise rigidly attached one end of the armature or reed 43. The other pole of the mag net is similarly equipped with a bracket 44 and has a bifurcated pole piece 45 in the arms of which are threaded the slotted studs 46 and '47. the smooth portions of which serve as adjustable poles for the speech coils 48 and 49. These speech 'coils are held in an insulated block 50 secured in position by a bolt 51. The connecting bar or link 52 is rigidly attached to the armature near its middle and the cone 53 may be of the kind above described.

With the armature or reed thus mounted on a resilient plate some of the movement of the free end of the armature may result from flexing the armature itself, and some may result from flexing the supporting plate 42.- 'Po1e piece 37 is suitably cut away beneath plate 42 to permit the desired movement of the plate and. to avoid any rattle or chatter at that point. This way of mounting the armature. contributes to 'ease -of production and to reliability-when the production is on a large scale or factory basis, and when from commercial considerations the factory output must be of uniform quality.

In all other respects the. modification shown in Figs. 13 and 14 is constructed and can be operated as heretofore pointed out in detail in connection with. the embodiments illustrated .in Figs. 3 and 4. VVith-either modification all of the mechanical parts, ineluding the diaphragm and actuating mechanism, are enclosed within 3 the casing formed by the frame 1 and covers 2 and 3.

In the drawings, the covers each consists of a narrow frame towhich is attached .What

may be conveniently termed an open work grille 31, consisting of woven cane. Any sort of perforated cover may be utilized, but the Woven cane presents an attractive appearance, is durable, and adds but little to the weight of the instrument.

Electrical connections are made to the instrument through the medium of a conduc torcord 26, terminal block 27, conductors 28, 29 and a pair of, binding posts 30, which may be secured'to the members 13.

'A. hinged lifting ring 32 provides a convenient means for lifting and carrying the instrument and "when not in use is practicallyout 'of sight.

'The whole structure itwill be seen is characterized by simplicity which is a virtue of very considerable importance. All parts of the instrument are easily accessible and are r of such form that they may be n'ianufactured with but a. very small outlay for special mechanism is particularly outstanding. This it is observed. comprises a very small number of parts all of which may be easily manufactured and quickly assembled without theneed for any unusual skill.'

The instrument is designed with a View to its being used as shown or, alternatively,

built into a cabinet such, for exan'iple. as a talking machine cabmet. 'Its form lends itself .particularly well for the latter purpose.

I claim:

1. In a translating device, the combination of a magnet, a face plate for one pole of said magnet, a polarized reed supported by said face plate and disposed substantially at right angles thereto, a S]')60(3l1 winding operatively positioned to flex said reed, and means connected to said reed intermediate 7 its ends for translating into sound the movements ofsaid reed.

2.111 a translating device, the combination of a magnet. a face plate detachably secured to one pole of said magnet, a polarized reed supported by said face plate and disposed at an angle thereto,a speech winding operatively positioned to flex said reed, and a conical diaphragm operatively con nected to said reed to translate, into sound the movements of said reed. i

3. .In a translating device, the. combination of a 1naguet,a face plate for one pole of said magnet, a polarized reed secured to said face plate and disposed transversely thereto, a speech winding o 'ieratively positioned td-act on said reed near its free end to flex said reed, and means connected to said reed between said windingand the remote end of said reed for translatmg mto sound the movements of said reed.

.tools. The simplicity of -the actuating and disposed atan angle thereto, a speech winding operatively positioned to act on said reed near its free end to flex said reed, and a conical dia hragm operatively connected to said reec to translate into sound the movements of said reed. V

5. In a translating device, the combination of a permanent magnet, a face plate secured to one pole of said magnet, a polarized reed carried by said face plate, two poles of a speech magnet on opposite sides of the free end of said reed and between which the free end of the reed' projects, and means for translating into sound the movements of said reed.

6. In a translating device, the combination of a permanent magnet, a plate detachably secured to one pole of said magnet, a

-\ polarized vibratory armature supported at one end by said plate, a bifurcated pole shoe embracing the other end of said armature and between the poles of which the free' end of said armature projects, a speech winding in magnetizing relation to said pole shoe, and means for translatinginto sound the vibratory movement of said armature.

7. In a translating device, the combination of a magnet, a support connected to one pole of said magnet, a polarized'vibratory armature secured at one end to said support, said armature being substantially at right angles to said support, a bifurcated pole shoe embracing the other end of said armature,

a speech winding in magnetizing relation to, ,said pole shoe, and a conical dlaphragm operatively connected to said armature to translate into sound the vibratory movements of said armature.

8. In a translating device, the combination of a magnet, a support secured to one pole of said magnet,-a polarized vibratory armature secured at one end to said support, said armature being substantially at right angles to said support, a bifurcated pole shoe embracing the other end of said armature, a speech winding in magnetizing relation to said pole shoe, and a conical diaphragm operatively connected to said armature intermediate its ends for translating into sound the vibratory movements of said armature.

9. In a translating device, the combination of a magnet, a support secured to one pole of said magnet, a polarized vibratory armature secured at one end to said support, a pole shoe embracing the other end of said armature, said shoe having two poles on opposite sides'of the free end of the armature and between which the free end of the armature projects, a speech coil for each pole shoe, each of said coils being held in stationary position with respect to the pole shoe and each pole being axially rotatable in the pole shoe and longitudinally adjustable through its speech coil.

10. In a translating device, the combination of a permanent magnet, a plate secured to one pole of said magnet, an armature tion of a permanent magnet, a plate detachably secured to one pole of said magnet, a flexible armature rigidly attached at one end to said plate, a soft iron pole shoe for the other pole of said magnet, said shoe having two opposed soft iron poles on opposite sides of the free end of said armature and between which the free end of the armature projects, a speech coil for each shoe pole,

and means for translating into sound-the movements of said armature produced ,by said speech coils.

12. In a translating device, the combination of a permanent magnet, a plate detachably secured to one pole of, said magnet, a flexible armature secured at one end to said 'plate, a soft iron pole shoe for the other pole of said magnet, said shoe having two opposed adjustable poles" on opposite sides of the free ends of said armature, a speech coil encircling each shoe pole, and means, including a diaphragm, for translating into sound the movements of said armature produced by said speech coils.

13. In a translating device, the combination of a permanent magnet, a plate detachably secured to one pole of said magnet, a steel armature attached at one end to said plate, a soft iron shoe for the other pole of said magnet, said shoe having two opposed adjustable poles on opposite sides of the free end of said armature, a speech coil encircling each shoe pole, a diaphragm for translating into sound the movements of said armature produced by said speech coils, and a rigid bar connecting the diaphragm to said armature near its middle.

14. In a translating-device, the combination of a permanent magnet, a. resilient plate detachably secured to one pole of said magnet, an armature attached at one end to said plate, a shoe forthe other polev of said magnet, said shoe having two opposed adjustable poles on opposite sides of the free ends of said armature, a speech coil encircling each shoe pole, and means,yincluding a diaphragm, for translating into sound the movements of said armature produced by said speech coils. i

- 15. In a translating device, the combination of a magnet, a resilient plate secured to one pole of said magnet, an armature supported at one end by said plate and dis- Loaders posed transversely thereto, a pole shoe for the other pole of said magnet, said shoe having two poles on opposite sides of the free end of said armature, a speech-coil for each shoe pole, and means for translatingdnto sound the movements of said armature producedby said speech coils,

16. In a translating device, the combina- *tion of a magnet, a resilient support secured to one pole of said magnet, a polarized vibratory armature secured at; one end to said support, a pole. shoe embracing the other end of the armature, said shoe having two poles on opposite sides of the free. end of the armature and between which the free end of the armaturepi'ojects, a speech coil for each pole, each ofsaid coilsbeing held in stationary position with respect to the'f' pole shoe and each'pole being axially rotatable in the pole shoe and longitudinally adjust able through its speech coil. 1 p -17. In a translating device, the combination of amagnet, a resilient plate 'cdetachably-secured to one pole of saidmagnet, a polarized vibratory armature supported at one end by said plate, said armature being' disposed transversely to saidplate, a bifurvibratory ture. combinaa tion' of a magnet, a resilient face plate for one pole oi said magnet, a polar zed reed secured-to. said face plate, said reed being substantially at right'angles to said plate, a speech winding operatively positioned to act on said reed near its free ends to flex the same,and means connected to said reed between said winding and the remote end of said reed for translating into sound the movements of said reed;

19, In a translating device, the combination-oi' a magnet, aresilient face plate detachably secured to one pole of said magnet,

plate and disposed substantially at right anpositioned "to vibrate said armature, and a a polarized armature supported by said i'ace gles thereto, a speech winding operatively' conical diaphragm operatively connected to Y saidarmature to translate into sound the movements of said reed.

26. In a translating device, the combina tion of 'a magnet, a resilient plate for one pole of said magnet, .a polarized armature.

supported at one end by said plate, said ar- .mature being substantially at right angles to said plate, a speech winding op'eratively positioned to vibrate said armature, and

means connected to said armature interme-' diate its ends for translating into sound the I movementsthereof. A

In testimony whereof I afiix my signaninou's o. HQPKINS. 

